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Date:   Thu, 1 Sep 2022 21:12:58 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Cc:     linux-media@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev,
        linux-kernel@vger.kernel.org, linux-staging@lists.linux.dev,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzk+dt@kernel.org>,
        Chen-Yu Tsai <wens@csie.org>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Samuel Holland <samuel@sholland.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Hans Verkuil <hans.verkuil@cisco.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Rob Herring <robh@kernel.org>
Subject: Re: [PATCH v6 1/6] dt-bindings: media: Add Allwinner A31 ISP
 bindings documentation
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References: <20220826184144.605605-1-paul.kocialkowski@bootlin.com>
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 <Ywk3W6pTOOlzLYVn@pendragon.ideasonboard.com>
 <YxDJtYgW/NYLw77u@aptenodytes>
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Hi Paul,

On Thu, Sep 01, 2022 at 05:03:17PM +0200, Paul Kocialkowski wrote:
> On Sat 27 Aug 22, 00:12, Laurent Pinchart wrote:
> > On Fri, Aug 26, 2022 at 08:41:39PM +0200, Paul Kocialkowski wrote:
> > > This introduces YAML bindings documentation for the Allwinner A31 Image
> > > Signal Processor (ISP).
> > > 
> > > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > > Reviewed-by: Rob Herring <robh@kernel.org>
> > > ---
> > >  .../media/allwinner,sun6i-a31-isp.yaml        | 97 +++++++++++++++++++
> > >  1 file changed, 97 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/media/allwinner,sun6i-a31-isp.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-isp.yaml b/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-isp.yaml
> > > new file mode 100644
> > > index 000000000000..2fda6e05e16c
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-isp.yaml
> > > @@ -0,0 +1,97 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/media/allwinner,sun6i-a31-isp.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Allwinner A31 Image Signal Processor Driver (ISP) Device Tree Bindings
> > > +
> > > +maintainers:
> > > +  - Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - allwinner,sun6i-a31-isp
> > > +      - allwinner,sun8i-v3s-isp
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  interrupts:
> > > +    maxItems: 1
> > > +
> > > +  clocks:
> > > +    items:
> > > +      - description: Bus Clock
> > > +      - description: Module Clock
> > > +      - description: DRAM Clock
> > > +
> > > +  clock-names:
> > > +    items:
> > > +      - const: bus
> > > +      - const: mod
> > > +      - const: ram
> > > +
> > > +  resets:
> > > +    maxItems: 1
> > > +
> > > +  ports:
> > > +    $ref: /schemas/graph.yaml#/properties/ports
> > > +
> > > +    properties:
> > > +      port@0:
> > > +        $ref: /schemas/graph.yaml#/properties/port
> > > +        description: CSI0 input port
> > > +
> > > +      port@1:
> > > +        $ref: /schemas/graph.yaml#/properties/port
> > > +        description: CSI1 input port
> > > +
> > > +    anyOf:
> > > +      - required:
> > > +          - port@0
> > > +      - required:
> > > +          - port@1
> > 
> > I'd still like to see all ports that exist in the hardware being
> > mandatory. I assume at least one of the A31 and V3s has two connected
> > ports in the SoC or you wouldn't declare them both here :-)
> 
> Some SoCs (e.g. A83T) only have one CSI controller so we can't require both.
> This could be a decision based on the compatible but my personal opinion is
> that it's not really worth making this binding so complex.
> 
> We can always informally enforce that all possible links should be present
> when merging changes to the soc dts.
> 
> What do you think?

It makes the binding more complex, but it allows catching issues in an
automated way instead of relying on reviews. Lowering the review burden
is something I usually welcome :-) It's probably less of an issue here
as this is all about the SoC integration, not about board files, so I
won't insist too strongly even if I prefer bindings that are more
descriptive.

> > Apart from that, this looks good.
> > 
> > > +
> > > +required:
> > > +  - compatible
> > > +  - reg
> > > +  - interrupts
> > > +  - clocks
> > > +  - clock-names
> > > +  - resets
> > > +
> > > +additionalProperties: false
> > > +
> > > +examples:
> > > +  - |
> > > +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> > > +    #include <dt-bindings/clock/sun8i-v3s-ccu.h>
> > > +    #include <dt-bindings/reset/sun8i-v3s-ccu.h>
> > > +
> > > +    isp: isp@1cb8000 {
> > > +        compatible = "allwinner,sun8i-v3s-isp";
> > > +        reg = <0x01cb8000 0x1000>;
> > > +        interrupts = <GIC_SPI 83 IRQ_TYPE_LEVEL_HIGH>;
> > > +        clocks = <&ccu CLK_BUS_CSI>,
> > > +             <&ccu CLK_CSI1_SCLK>,
> > > +             <&ccu CLK_DRAM_CSI>;
> > > +        clock-names = "bus", "mod", "ram";
> > > +        resets = <&ccu RST_BUS_CSI>;
> > > +
> > > +        ports {
> > > +            #address-cells = <1>;
> > > +            #size-cells = <0>;
> > > +
> > > +            port@0 {
> > > +                reg = <0>;
> > > +
> > > +                isp_in_csi0: endpoint {
> > > +                    remote-endpoint = <&csi0_out_isp>;
> > > +                };
> > > +            };
> > > +        };
> > > +    };
> > > +
> > > +...

-- 
Regards,

Laurent Pinchart